#pragma GCC optimize(2)
#include <iostream>
#include <algorithm>
#include <cstring>
#include <string>
#include <map>
#include <vector>

using namespace std;
using LL = long long;
/*
we can suppose that character c is at the end of palidrome, the num of c is n
so we can get n*(n + 1)/2 palindrome at most
it easy to see, that sorted string satified this condition
*/

int main(){
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    string s;
    cin >> n >> s;

    sort(s.begin(), s.end());
    cout << s << '\n';

    return 0;
}